Quenching apparatus



March 27, 1962 s. s. JOHNSTON ETAL 3,026,884

QUENCHING APPARATUS Filed Dec. '7, 1956 INVENTOR SAMUEL .5. JOHNS TON GEOR? L. FREAS BY r M) ATTORNEY 3,026,884 QUENHENG AEPARATUS amuel S. Johnston and George L. Frees, Steubeuvillc,

Ghio, assiguors to National Steel Corporation, a corporation of Delaware Filed Dec. 7, 1956, Ser. No. 626,928 6 Claims. (tCl. 134-122) The present invention relates to quenching apparatus and more particularly to improved apparatus for quenching metal strip traveling at high strip speeds.

in the present day, high speed production of electrolytic tinplate, ferrous metal strip such as black plate, is continuously passed through an electroplating line at strip speeds of 500 to 2000 feet per minute, or higher. As the ferrous metal strip passes through the electroplating line, it is electroplated with a coating of tin of desired thickness. The amount of tin deposited on the ferrous metal strip is relatively small when compared with tinplate produced by the hot dip process and usually varies from about one-quarter pound to one pound per base box. The tinplate leaving the final electroplating cell in the electroplating line has a dull or matte finish and, normally, the electroplated tinplate is washed and passed through suitable flow-brightening apparatus. As the tin-plate with a matte surface passes through the flow-brightening apparatus, the tin coating is heated to a temperature above its melting point so that the tin will flow. Preferably, the molten tin is immediately quenched and solidified. Upon quenching the flow-brightened tinplate in a suitable quenching apparatus, the tinplate will then have a bright, mirror-like surface and it is a more desirable product.

The flow-brightening and quenching steps generally follow shortly after the tinplate leaves the electroplating cell. The quenching apparatus is normally incorporated as an element within modern electroplating lines and thus must be capable of quenching the tinplated strip at the strip speed employed, i.e., up to 2000 feet per minute, or even higher. However, when quenching tinplated strip at these high strip speeds, for some reason the strip tends to vibrate or oscillate excessively as it is passed through the quenching apparatus. As a result, there is interference with the quenching operation and its function is impaired.

We have discovered that the above mentioned difficulty may be overcome by transmitting opposed forces or pressures laterally against the strip in the vicinity of the lower area of the quench box. For some reason or reasons not fully understood at the present time, such opposed forces or pressures have been found to prevent vibration or oscillation of the strip at the strip speeds at which it is desired to operate the electroplating line.

It is a principal object of the present invention to provide improved apparatus for quenching metal strip.

lt is a further object of the present invention to pro vide improved apparatus for quenching metal strip moving at high strip speeds, whereby objectionable vibrating or oscillating movement of the metal strip at certain strip speeds is prevented.

Still other objects of the present invention and the advantages thereof will be apparent from the following detailed description and the accompanying drawing, wherein:

FIG. 1 is a diagrammatic sectional view of a presently preferred embodiment of the present invention in its environment;

FIG. 2 is a plan view of the novel quench box of the present invention taken along the line 2 2 of FIG. 1;

FIG. 3 is a cross-sectional view taken along the line 33 of FIG. 2; and

FIG. 4 is a longitudinal sectional view taken along the line 4-4 of FIG. 2.

3,h26,884 Patented Mar. 27, 19:62

Referring now to the drawings, the quenching apparatus generally designated as 1 comprises quench tank 2 filled to a predetermined level with water or other suitable fluid quenching medium 3. The level 8 of quenching medium 3 may be conveniently controlled by the height of the upper opening 5 of discharge pipe 4, or by other suitable means. When the level 8 of fluid medium 3 rises to a sufiicient height, quenching medium 3 is withdrawn through opening 5 and flows downward through discharge pipe 4, and it is then discharged at 6. The height of quench tank 2 and the depth of quenching medium 3 is such as to allow quench box 7 to be mounted in quench tank 2 with sufficient clearance between manifolds 20 and 21 and the bottom of quench tank 2 for convenient operation of other component elements of quenching apparatus 1.

A quench box '7 having a generally rectangular configuration is mounted in quench tank 2. The quench box 7 is provided with top and bottom openings 10 and 11, respectively, extending substantially the length of quench box 7. The top and bottom openings 10 and 11 form an entrance and an exit, respectively, to quench box 7 for metal strip S. The quench box 7 is immersed in quenching medium 3 to a depth allowing the upper opening it to remain above the level 8 of quenching medium 3. The top of quench box 7 may be entirely open, as shown, with the top opening 10 extending subst-antially across the width of quench box '7. The bottom opening 11 may have a width appreciably less than that of quench box 7, thereby allowing for convenient arrangement of other cooperating elements. Preferably, the bottom of quench box 7 is partially closed by longitudinally extending bottom portions 12 and 14.

The metal strip S to be quenched, e.g., tinplated ferrous metal strip from the fiow-brightener of an electroplating line traveling at a high strip speed, is passed through top opening 10 into the upper portion of quench box "7, where it is contacted with fresh quenching medium 3. The metal strip 8 is passed downward through quench box 7, and through bottom opening ll into quench tank 2. The metal strip S is then passed downward in quench tank 2 and under roll 3%, which is mounted in the lower portion of quench tank 2 by means of pin 31, and upward in quench tank 2. The metal strip S, after quenching, is withdrawn from the top of quench tank 2 and then may be passed to drying apparatus, or given any other desired treatment. I

Inwardly inclined battles 15 and 16 are formed along the inner edges of bottom portions 12 and 14, respectively, and along top opening 11. The baffles 15 and 16- are shown as extending substantially the len th of quench box 7 and upward slightly more than half the height of quench box 7. One important function of battles 15 and it) is to direct fresh quenching medium 3 against the surfaces of metal strip S as the same enters quench box 7 and passes downwardly in the upper portion of quench box 7. The baflies l5 and 16 should not be inclined to such an extent as to allow contact with metal strip S and thus mar or otherwise damage the surface of the same.

The bafiles l5 and in are provided with narrow, longitudinally extending slots 28 and 29, respectively. The slots 28 and 2% may have a width of about one-eighth inch, and extend to within a short distance of the ends of balles l5 and 16. The purpose of slots 28 and 29 is to allow incoming fresh quenching medium 3 to jet inwardly and toward metal strip S, thereby providing opposed lateral forces or pressures against metal strip S. This arrangement has been found to be both an eitective and convenient means for providing the opposed forces or pressures against strip S in the lower portion or area of quench box 7, which are necessary for preventing undesirable vibration or oscillation of strip S when traveling at high strip speeds. However, it will be apparent to those skilled in the art that other suitable means may be provided for causing opposed forces or pressures to bear against metal strip S in the lower area of quench box 7, or the vicinity thereof, for this purpose. For example, opposed streams of quenching medium 3, auxiliary in nature, may be allowed to impinge upon strip S in a suitable manner.

Fresh quenching medium 3 under pressure is supplied to feed pipes 17 and 18 from a suitable source (not shown) via supply pipe 19. The feed pipes 17 and 18, in turn, supply fresh quenching medium 3 to manifolds 20 and 21, respectively. Each of the manifolds 2t and 21 is provided with a plurality of similar spaced conduits 22 leading upward through bottom portions 12 and 14 of quench box 7 and into the lower portion of the areas 32 and 33 between vertical walls 23 and 7.4 of quench box 7 and bafiles 15 and 16, respectively, for this purpose of supplying fresh quenching medium 3 uniformly to quench box 7 along substantially its entire length. A major portion of the fresh quenching medium 3 so supplied is then directed upward and inward in quench box 7 by baffies 15 and 16 and toward that portion of strip S which is in the upper portion of quench box 7. A portion of the upwardly directed quenching medium 3 continues to flow upward through quench box 7, and overflows the sides thereof into quench tank 2, while an appreciable portion of the upwardly directed quenching medium 3 is pulled downward by strip S and through bottom opening 11. A minor portion of fresh quenching medium 3 jets through slots 28 and 29, and inward toward that portion of strip S which is in the lower portion of quench box 7, thereby providing opposed forces or pressures against strip S.

The supply line 19 is provided with a valve 25, which is controlled by valve operator 26 in response to temperature data fed by thermostat 27. The valve is preferably of a type which is cracked even when in the closed position, thereby insuring a small flow of cooling medium 3 at all times. The thermostat 27 should be placed a short distance from the incoming strip S to insure that the temperature recorded thereby will c osely approximate the actual temperature of cooling medium 3 in contact with strip S. For example, the thermostat 27 should be placed a distance of aproximately 1 to 3 inches from strip S for best results. The temperature of cooling medium 3 may be of critical importance and particularly when water is the cooling medium. If quench stains or snowballs are to be prevented when quenching flowbrightened tinplate with water as the quenching medium, it is highly desirable that the temperature of water in contact with the flow-brightened tinplated strip to be quenched be closely controlled. When quenching flowbrigh-tened tinplate with water, the preferred temperature of the water varies with the amount of tin deposited on the strip. For example, when about one-quarter pound of tin per base box is deposited on the surface of the metal strip, the preferred temperature of the quench water is 70 F. to 90 F., while with metal strip having about one pound of tin deposited on the surface, a temperature of about 165 F. to 175 F. is preferred. If more than about one-quarter pound and less than about one pound of tin is deposited on the metal strip surface, a temperature intermediate the above mentioned temperatures is preferred. For example, when one-half pound tinplate is to be quenched, a temperature of 130 F. to 140 F. is preferred and, when three-quarter pound tinplate is to be quenched, a temperature of about 145 F. to 165 F. is preferred. The temperature of the quenching medium in contact with the flow-brightened strip may be conveniently controlled by varying the flow rate of fresh quenching medium 3 by means of valve 25. he flow rate of fresh quenching medium 3 to quench box 7 may be caused to increase by means of valve operator 26 when the temperautre rises above a predetermined value, as recorded by thermostat 2"], or the flow rate may be caused to decrease when the telnerature, as recorded by thermostat 27, falls below a predetermined value.

When quenching apparatus 1 is used in a modern electroplating line for quenching flow-brightened tinplate having molten tin on its surface, the tinplated strip S enters quench box '7 through top opening 10 at high strip speeds of 500 to 2000 feet per minute. The tinplated strip S is passed downward in quench box 7, where it is contacted in the upper portion therof with fresh quenching medium 3, which immediately cools and solidifies the molten tin. To insure proper quenching of tinplated strip S, normally, fresh quenching medium 3 is continuously supplied to the lower portion of quench tank 7 from a suitable source via supply pipe 19, feed pipes 17 and 18, manifolds 20 and 21, and conduits 22. A major portion of the fresh quenching medium 3 so supplied is then directed upward and inward in quench box 7 by baffles 15 and 16 and toward that portion of tinplated strip S which is in the upper portion of quench box 7, thereby insuring immediate quenching of the molten tin on the surface of tinplated strip S. A portion of the upwardly directed quenching medium 3 continues to flow upward through quench box 7, and overflows the sides thereof into quench tank 2, while an appreciable portion of the upwardly directed quenching medium 3 is pulled downward by strip S and through bottom opening 11. A minor portion of fresh quenching medium 3 jets through slots 28 and 29, and inward toward that portion of tinplated strip S which is in the lower portion of quench box 7, thereby providing opposed forces or pressures against tinplated strip S for preventing undesirable vibration or oscillation of tinplated strip S at any strip speed at which it is desired to operate the electroplating line. The tinplated strip S is then withdrawn from quench box 7 through bottom opening 11 and passed downward into quench tank 2, under roll 30, and upward and out of quench tank 2. The quenched tinplated strip S is then ready for passing to drying apparatus or other desired subsequent treatment.

While the use of quenching apparatus 1 has been specifically described above in connection with its use in a high speed electroplating line for quenching flowbrightened tinplated strip, it will be recognized by those skilled in the art as being useful for quenching other forms of metal strip or other elongated metal forms, in general, wherever a quenching operation is desirable.

The foregoing detailed description of a presentlv preferred embodiment of the invention and the drawing are for purposes of illustration only, and are not to be taken as being limiting to the scope or spirit of the appended claims.

What is claimed is:

1. Apparatus for quenching metal strip comprising a quench tank, a quench box mounted in the quench tank, the quench box having openings in the top and bottom forming an entrance and an exit for longitudinal movement therethrough of the metal strip to be quenched, means for passing metal strip through the quench box, longitudinally extending baffles in the bottom portion of the quench box in spaced relationship with respect to each other and the sides of the quench box, means operatively connected with the quench box for introducing fluid quenching medium under pressure into the spaces between the battles and the sides of the quench box, and means in the quench tank in the vicinity of the bottom opening in the quench box for transmitting opposed fluid forces laterally and inwardly with respect to the bafiles.

2. Apparatus for quenching metal strip comprising a quench tank, a quench box mounted in the quench tank, the quench box having openings in the top and bottom forming an entrance and an exit for longitudinal movement therethrough of the metal strip to be quenched, means for passing metal strip through the quench box, baflles in the quench box in spaced relationship, the baflies being constructed and arranged in the quench box so as to extend along the bottom opening and upward to about half the distance between the top and bottom openings thereby forming spaces between the baflles and the sides of the quench box, means operatively connected with the quench box for introducing fluid quenching medium under pressure into the spaces between the baffles and the sides of the quench box, and means in the quench tank in the vicinity of the bottom opening in the quench box for transmitting opposed fluid forces laterally and inwardly with respect to the baffles.

3. Apparatus for quenching metal strip comprising a quench tank, a quench box mounted in the quench tank, the quench box having openings in the top and bottom forming an entrance and an exit for longitudinal movement therethrough of the metal strip to be quenched, means for passing metal strip through the quench box, inwardly inclined longitudinally extending baflles in the bottom portion of the quench box in spaced relationship with respect to each other and the sides of the quench box, the baifles having openings formed in their respective lower portions and means operatively connected with the quench box for introducing fluid quenching medium under pressure into the spaces between the bafiies and the sides of the quench box.

4. Apparatus for quenching metal strip comprising a quench tank, a quench box mounted in the quench tank, the quench box having openings in the top and bottom forming an entrance and an exit for longitudinal movement therethrough of the metal strip to be quenched, means for passing metal strip through the quench box, inwardly inclined baffles in the quench box in spaced relationship, the bafiles being constructed and arranged in the quench box so as to extend along the bottom opening and upward to about half the distance between the top and bottom openings thereby forming spaces between the baflies and the sides of the quench box, the bafiles having openings formed in their respective lower portions and near the bottom opening in the quench box, and means operatively connected with the quench box for introducing fluid quenching medium under pressure into the spaces between the bafiies and the sides of the quench box.

5. Apparatus for quenching metal strip comprising a quench tank, a quench box mounted in the quench tank, the quench box having openings in the top and bottom forming an entrance and an exit for longitudinal movement therethrough of the metal strip to be quenched, means for passing metal strip through the quench box, inwardly inclined longitudinally extending baffles in the bottom portion of the quench box in spaced relationship with respect to each other and the sides of the quench box, the baflles having narrow longitudinally extending slots formed in their respective lower portions, and means operatively connected with the quench box for introducing fluid quenching medium under pressure into the spaces between the baflles and the sides of the quench box.

6. Apparatus for quenching metal strip comprising a quench tank, a quench box mounted in the quench tank, the quench box having openings in the top and bottom forming an entrance and an exit for longitudinal move ment therethrough of the metal strip to be quenched, means for passing metal strip through the quench box, inwardly inclined bafiles in the quench box in spaced relationship, the battles being constructed and arranged in the quench box so as to extend along the bottom opening and upward to about half the distance between the top and bottom openings thereby forming spaces between the baffles and the sides of the quench box, the baflles having narrow longitudinally extending slots formed in their respective lower portions and near the bottom opening in the quench box, and means operatively connected with the quench box for introducing fluid quenching medium under pressure into the spaces between the baffles and the sides of the quench box.

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